Chain driven positioning device methods and systems

ABSTRACT

Aspects of the present invention relate to providing a chain driven positioning device. In embodiments, methods and systems are provided for the chain driven positioning device use in a vacuum environment. A method and system of a positioning device, providing a positioning arm; and driving the positioning arm with a chain.

BACKGROUND

1. Field

This invention relates to the methods and systems for a chain driven positioning device and more generally to the field of providing a chain driven positioning device for use in a vacuum environment.

2. Background

A positioning device may be a device used for repetitive operations, working in hostile environments, working in environments that people are not able to work, or for high volume work. The positioning devices typically have at least one moveable positioning arm to allow the positioning device to move objects from one location to another. The construction of the positioning arms used by the positioning devices typically includes at least one rotating shaft, at least one pulley, and at least one belt. The belt may be of a polymer type with reinforcing materials, similar to the belts used on an automobile engine. The belts may be used with pulleys, with the pulleys attached to the driving rotating shafts.

Belts can become worn and stretched over time, requiring maintenance to replace the belts. In some environments, the replacement of the belts may require the shut down of a system to allow access to the belts, adding to the cost of operating the positioning device and the system it supports. The belts may also become an issue in some environments, such as a vacuum system, where the belts may out gas during the vacuum pump down process.

Accordingly, a need exists for a positioning device that uses alternate materials for the belt to provide long life with minimal service requirements and can be used in many different environments.

SUMMARY

Provided herein are methods and systems for providing a positioning arm; and driving the positioning arm with a chain. The chain may be a bicycle type chain. There may be at least one chain in the positioning arm. The chain material may be at least one of stainless steel, nickel plated steel, aluminum, and titanium. The positioning arm may contain at least two sprockets. The sprocket teeth may engage the chain. The sprockets may be the same size or the sprockets may be a different size. The sprocket material may be at least one of stainless steel, nickel plated steel, aluminum, and titanium. A chain drive position arm may contain the chain, at least two sprockets, and the positioning arm. At least one sprocket may be a drive sprocket mounted on a rotating shaft.

A positioning device may contain at least one chain drive position arm. The chain drive position arm may be in a vacuum. The chain drive position arm may have a lubrication material. The lubrication material may be at least one of a vacuum compatible grease and perfluorinated hydrocarbons. A sealed lubrication enclosure may contain a flexible container, the lubrication material, at least one chain, and at least one sprocket. The flexible container may be a polymer material. The sealed lubrication enclosure may have a fixed seal on a rotating shaft. The fixed seal may partially twist the flexible container during the chain drive position arm movement. The chain drive position arm may rotate less than 360 degrees on the rotating shaft. The sealed lubrication enclosure may be evacuated of gases. A self-sealing spring may provide the fixed seal on the rotating shaft when the gases are evacuated.

A self-adjusting tensioner may maintain the chain tension during operation. There may be at least one self-adjusting tensioner for the chain. The self-adjusting tensioner may contain a spring, the chain, and a ratchet. There may be at least one ratchet. The spring may push the chain into the self-adjusting tensioner. The spring may push the chain toward the ratchet when the chain is not in tension. The ratchet may engage a chain link. The spring may push the chain link onto the ratchet. The chain may be in tension when the ratchet locks on the chain link.

BRIEF DESCRIPTION OF FIGURES

The chain drive positioning device may be understood by reference to the following figures:

FIG. 1 shows an embodiment of the top and side view for a chain drive positioning device.

FIG. 2 shows an embodiment of a sealed lubrication enclosure for the chain drive positioning device.

FIG. 3 shows the oscillating motion of the chain drive positioning device.

FIG. 4 shows an embodiment of a self-adjusting tensioner on the chain and a detailed embodiment of the self-adjusting tensioner.

DETAILED DESCRIPTION OF FIGURES

Referring to FIG. 1, an embodiment of a positioning arm 100 is shown in both a top view and a side view. A positioning arm 100 may be used on a positioning device such as a robot for picking and placing operations, lifting operation, or operation in a hostile environment. It would be obvious to a person knowledgeable in the art that the positioning arm 100 may be used in association with additional positioning arms to allow additional reach or add additional axis of motion for a robotic device. The additional positioning arms may be placed in relation to the first positioning arm 100 to allow the required reach for the device. The positioning arm 100 may have a covering 102 to protect the positioning hardware from damage, structural strength, or for safety reasons.

The positioning arm 100 may contain a chain 110, sprockets 104 108, and rotating shaft 114 118. The chain 110 may be driven by a drive sprocket 104 that may be mounted on a rotating shaft 114. The chain 110 may engage at least one additional sprocket 108 on a shaft 118, this sprocket 108 and shaft 118 may be used to drive an additional positioning arms that may be connected to the shaft 118. The sprockets 104 108 of the positioning arm 100 may be the same diameter or of differing diameters. Sprockets 104 108 that are the same size may provide a one to one positioning ratio for the positioning arm 100, sprockets 104 108 of a different size may provide a gearing ratio that may allow the positioning arm 100 to move faster or slower than the rotating shaft 114 of the drive sprocket 104. It would be obvious to a person knowledgeable in the art that a robotic device may have a plurality of rotating drive shafts 112 114 for the positioning of a plurality of positioning arms or providing multiple axis motion to the robotic device.

The use of a chain 100 to drive the positioning arm 100 may be superior to other types of drive devices, such as a belt, that may slip as it becomes worn or loose in time. A belt that allows slippage between the belt and the rotating shafts may provide reduced positioning precision than a chain that is locked on the teeth of a sprocket. The chain 110 engagement to the sprockets 104 108 may provide a not slip configuration by the chain 1 10 interlocking with the teeth of the sprockets 104 108.

It should be understood that the chain 110 may be made of different materials and sizes (e.g. thickness of material, height, width, or length) to provide the tension strength required by positioning arm 100. The chain 110 and sprocket 104 108 material may be at least one of stainless steel, nickel plated steel, aluminum, and titanium. It should also be understood that there may be more than one chain 1 10 and sprocket 104 108 assembly in a positioning arm. For example, a second chain and sprocket may be used for additional strength on the same rotating shaft or may be used to drive more than one additional positioning arm on a second rotating shaft. The additional chain and sprocket assembly may use a different sprocket diameter and may be driven by a different rotating shaft.

Referring to FIG. 2, an embodiment of a sealed lubrication enclosure 200 for the positioning arm 100, chain 110, and sprockets 104 108 as described in FIG. 1 is shown. It should be understood that moving interlocking metallic parts may require lubrication to allow for a continued smooth working action over an operating life. A positioning arm 100 may operate in a plurality of environments including a vacuum atmosphere. Vacuum systems are very sensitive to materials such as lubricants in the vacuum containment volume. Materials such as lubricants, even vacuum specific lubricants, tend to out gas (e.g. the release of a gas within a material during a vacuum pump down) at a slow rate and may require a substantial amount of time to achieve the required vacuum. The slow out gassing of the lubricant may significantly increase the vacuum pump down time and therefore may significantly increase the cost of the vacuum operation.

A sealed lubrication enclosure 200 may be used to enclose the chain 110 and sprockets 104 108 as described in FIG. 1. The sealed lubrication enclosure 200 may be made of a polymer or similar material. The sealed lubrication enclosure 200 may be filled with lubricant such as vacuum compatible grease or perfluorinated hydrocarbons. The sealed lubrication enclosure 200 may completely enclose the chain 110 and sprockets 104 108 maintaining a continuous lubrication of the chain [10 and sprockets 104 108. The sealed lubrication enclosure 200 may have a fixed seal 204 for at least one of the rotating shafts maintaining a seal between the lubrication and the vacuum environment. The fixed seal 204 may provide a tight fit to prevent the lubricant of the sealed lubrication enclosure 200 from out gassing into the vacuum containment during the vacuum pump down cycle. To further reduce any out gas from the lubricant, the sealed lubrication enclosure 200 may have any lubricant gas evacuated as part of the sealed lubrication enclosure 200 assembly process. During the sealed lubrication enclosure evacuation process a self-sealing spring may provide a tight seal for at least one shaft. The sealed lubrication enclosure 200 may have a fixed seal 204 at any of the rotating shafts associated with the positioning arm.

When the rotating shaft rotates, the sealed lubrication enclosure 200 may twist at the fixed seal 204 without tearing. There may be an interface 202 between the fixed seal 204 and the sealed lubrication enclosure 200 to aid in the twisting of the sealed lubrication enclosure. The interface 202 may have extra material or may have an accordion type design to allow the twisting required by the positioning arm motion.

In an embodiment, with the fixed seal 204 in place for at least one rotating shaft, the positioning arm 100 may be limited in the rotational travel. Instead of rotating a full 360 degrees, the positioning arm 100 with a sealed lubrication enclosure 200 may oscillate back and forth to reach all of the required positions for the positioning device. There may be a limiting device (e.g. mechanical, electrical, or programmed) to limit the rotation motion of the positioning arm 100.

Referring to FIG. 3, an embodiment of the restricted rotation of the positioning arm 100 is shown. As described in FIG. 2, there may be a limit on the rotation of the positioning arm 100 because of the fixed seal 204 of the sealed lubrication enclosure 200. For example, if a positioning arm 100 moved from position 304 to position 308 it may move along path 300 in a counter clockwise direction. If the next required motion was to go from position 308 to position 310, the position arm 100 may not continue to move in the counter clockwise direction because of the restricted motion of the sealed lubricated enclosure 200. The positioning arm 100 may instead move clockwise along path 300 past position 304 and on to position 310 along path 302. It should be understood that the limit of the motion for the position arm 100 may be a function of the amount of rotation permitted by the sealed lubrication enclosure 200 without tearing. There may be a limiting device (e.g. mechanical, electrical, or programmed) to limit the rotation motion of the positioning arm 100.

Referring to FIG. 4, an embodiment of a self-adjusting tensioner 400 is shown. Over the operational life of the positioning arm 100, the chain 110 may stretch or elongate from the tensile load on the chain 110. Since the positioning arm 100 may be in a vacuum environment, the chain 110 may be fully enclosed in a sealed lubrication enclosure 200 and the chain may not be serviceable. In order to maintain the useful life of the chain 110, a self-adjusting tensioner 400 may be used. The self-adjusting tensioner 400 may be positioned on the chain 110 to remove any slack that may develop over time. There may be at least one self-adjusting tensioner 400 on a chain 110. It should be understood that during the motion of the chain 110 around the sprockets 104 108, one side (the pull side) of the chain 110 may be in tension but the opposite site (the push side) may have less tension. The tension and less tension sides of the chain 110 may be dependent on the direction of rotation of the chain 110 around the sprockets 104 108. The self-adjusting tensioner 400 may be able to remove slack in the chain 100 while the self-adjusting tensioner 400 is on the less tension side of the chain 110. It should be understood that if a self-adjusting tensioner 400 is positioned on both sides of the chain 110, the tension of the chain 110 may be adjusted with each chain 110 motion because one of the self-adjusting tensioners would always be on a less tension side of the chain 110 and allow for tension adjustment.

The detail of the self-adjusting tensioner 400 shows one embodiment of a self-adjusting tensioner 400 design. One end of the chain 410 may be connected to one side of a housing 418. The other end of the chain 402 may pass into the housing 418 and connect to a plate 414. The plate 414 may not be anchored to the housing 418 and may be free moving within the housing 418 or the plate 414 may be attached to the housing 418 using a slide to allow freedom of motion within the housing 418. The chain 402 may also pass through a spring 404, the spring 404 may be positioned between housing 418 and the plate 414. The spring 404 may be of a large enough diameter to allow the chain 402 to pass inside the spring 404 diameter and connect to the plate 414. The spring 404 may be compressed between the housing 418 and the plate 414 when the chain 402 is extended to its max length. With the spring 404 in compression, a force in a direction 408 is applied to the chain 402 exerting a force on the chain 402 to “push” the chain 402 into the housing 418. The spring 404 push on the chain 414 into the housing 418 may remove slack from the chain 110.

To maintain rigidity in the chain 110 when the chain 110 is in tension, the self-adjusting tensioner 400 may have a ratchet 412 that may engage and lock the chain 402. It would be obvious to a person knowledgeable in the art that the location, design, and number of ratchets may vary based on the selected chain 110, spring 404, and housing 418 design. During a move sequence of the chain 110, when the self-adjusting tensioner 400 is on the less tension side of the chain 110, the spring may push the slack chain 402 into the housing 418. The ratchet 412 may automatically lock onto the closest chain 402 link when the spring 404 pushes the chain 402 into the housing. Once the ratchet 412 has locked onto a chain 402 link the chain will be constrained for the next move that has the chain 402 in tension. It should be understood that the self-adjusting tensioner 400 may have at least one ratchet 412. With every chain 110 move the self-adjusting tensioner 400 may attempt to adjust the chain link that the ratchet 412 is locked on. It should be understood that the ratchet 412 may only lock onto an different chain link when the chain 110 has stretched enough to permit locking onto a different chain link.

While the invention has been described in connection with certain preferred embodiments, other embodiments would be understood by one of ordinary skill in the art and are encompassed herein. 

1. A method of operating a positioning device, comprising: providing a positioning arm; and driving the positioning arm with a chain.
 2. The method of claim 1 wherein the chain is a bicycle type chain.
 3. The method of claim 2 wherein at least one chain is in the positioning arm.
 4. The method of claim 2 wherein the chain is formed of a material including at least one of stainless steel, nickel plated steel, aluminum, and titanium.
 5. The method of claim 1 wherein the positioning arm includes at least two sprockets.
 6. The method of claim 5 wherein the at least two sprockets engage the chain with one or more teeth.
 7. The method of claim 5 wherein the at least two sprockets are of equal size.
 8. The method of claim 5 wherein the at least two sprockets are of different sizes.
 9. The method of claim 5 wherein the at least two sprockets are formed of a material including at least one of stainless steel, nickel plated steel, aluminum, and titanium.
 10. The method of claim 5 wherein the at least two sprockets include a drive sprocket mounted on a rotating shaft.
 11. The method of claim 1 wherein the positioning device includes at least one chain drive position arm.
 12. The method of claim 11 wherein the chain drive position arm is within a vacuum.
 13. The method of claim 11 wherein the chain drive position arm includes a lubrication material.
 14. The method of claim 13 wherein the lubrication material includes a vacuum compatible grease and a perfluorinated hydrocarbon.
 15. The method of claim 13 further comprising forming a sealed lubrication enclosure from the lubrication material, a flexible container, at least one chain, and at least one sprocket.
 16. The method of claim 15 wherein the flexible container is formed of at least one polymer.
 17. The method of claim 15 wherein the sealed lubrication enclosure includes a fixed seal on a rotating shaft.
 18. The method of claim 17 wherein the fixed seal partially twists the flexible container during a movement of the at least one chain drive position arm.
 19. The method of claim 18 wherein the at least one chain drive position arm rotates less than 360 degrees on the rotating shaft.
 20. The method of claim 15 further comprising evacuating a gas from the sealed lubrication enclosure.
 21. The method of claim 20 wherein a self-sealing spring provides the fixed seal on the rotating shaft when the gases are evacuated.
 22. The method of claim 1 further comprising maintaining a tension in the chain during operation with a self-adjusting tensioner.
 23. The method of claim 22 further comprising maintaining a tension in the chain during operation with a plurality of self-adjusting tensioners.
 24. The method of claim 22 wherein the self-adjusting tensioner includes a spring, a ratchet, and the chain.
 25. The method of claim 24 wherein the self-adjusting tensioner includes a plurality of ratchets.
 26. The method of claim 24 further comprising pushing the chain into the self-adjusting tensioner with the spring.
 27. The method of claim 26 further comprising pushing the chain toward the ratchet with the spring when the chain is not in tension.
 28. The method of claim 24 further comprising engaging a link of the chain with the ratchet.
 29. The method of claim 28 further comprising pushing the link onto the ratchet with the spring.
 30. The method of claim 24 wherein the chain is in tension when the ratchet locks on to the link. 